For refcode 2002MNRAS.334L..11A: Retrieve 6 NED objects in this reference. Please click here for ADS abstract
NED Abstract
Copyright by Royal Astronomical Society.
2002MNRAS.334L..11A
Cosmological constraints from the Xray gas mass fraction in relaxed
lensing clusters observed with Chandra
S. W. Allen, R. W. Schmidt and A. C. Fabian
ABSTRACT
We present precise measurements of the Xray gas mass fraction for a sample
of luminous, relatively relaxed clusters of galaxies observed with the
Chandra observatory, for which independent confirmation of the mass results
is available from gravitational lensing studies. Parametrizing the total
(luminous plus dark matter) mass profiles using the model of Navarro,
Frenk & White, we show that the Xray gas mass fractions in the clusters
asymptote towards an approximately constant value at a radius r_2500_,
where the mean interior density is 2500 times the critical density of the
Universe at the redshifts of the clusters. Combining the Chandra results
on the Xray gas mass fraction and its apparent redshift dependence with
recent measurements of the mean baryonic matter density in the Universe and
the Hubble constant determined from the Hubble Key Project, we obtain a
tight constraint on the mean total matter density of the Universe,
{OMEGA}_m_ = 0.30_0.03_^+0.04^, and measure a positive cosmological
constant, {OMEGA}_{LAMBDA}_ = 0.95_0.72_^+0.48^. Our results are in good
agreement with recent, independent findings based on analyses of
anisotropies in the cosmic microwave background radiation, the properties
of distant supernovae, and the largescale distribution of galaxies.
Keywords: gravitational lensing  galaxies: clusters: general 
cosmological parameters  Xrays: galaxies: clusters.
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